The present invention relates to a compact radio equipment such as a cell phone or radio communication terminal, and a mounting method thereof.
Conventionally, when electric circuits divided into two or more blocks and mounted on two or more printed circuit boards are mounted in the equipment, a first printed circuit board and a second printed circuit board are electrically connected using one of various kinds of connectors or pin contact systems. A frame is mounted between the first and second printed circuit boards not only to protect the electric circuits on the first printed circuit board, but also position and fix the second printed circuit board (see JP-A-2001-111232).
The conventional frame mentioned above is molded of resin, or made from die cast alloy. The second printed circuit board is secured with screws or engaged with hooks. In case of a resin molded frame, a certain thickness is required in the manufacturing process. The increased thickness of the frame is the cause of preventing the achievement of a small, thin radio equipment design.
The use of screws to secure the second printed circuit board requires an additional step of attaching the screws at manufacturing facilities, and this reduces workability.
On the other hand, the use of hooks to secure the second printed circuit board causes another problem that the hooked portions are susceptible to damage. The die cast alloy is suitable for making the equipment small and thin, but manufacturing costs are high. It may also require an additional step of attaching screws like in the case of resin molding.
Further, the use of a connector or pin contact system to electrically connect the electric circuits on the first printed circuit board and the electric circuits on the second printed circuit board is not enough to supply adequate ground potential. Therefore, a resin molded frame with aluminum deposited on it is used as a conduction material. In other words, metal springs or pins are mounted on the first and second printed circuit boards so that they will electrically contact the aluminum deposited frame. Thus, the supply of the ground potential is enhanced.
However, since aluminum deposition is expensive, the cost of a resin molded frame with aluminum deposited on it becomes high.
Further, since the resin molded frame with aluminum deposited on it is of a contact type, adequate conductivity cannot be obtained. In this case, since not only is the supply of the ground potential inadequate, but the thermal conductivity is also insufficient, heat may be built up in a local place.